Magnetic type pressure operated snap switch



July 14, 1964 L. BEEMAN 3,141,077

MAGNETIC TYPE PRESSURE OPERATED SNAP SWITCH Filed Jan. 13, 1964 2 Sheets-Sheet 1 2 INVENTOR. 46" .1 F45 Eff/14A V ATTOR/VA'YS July 14, 1964 L. BEEMAN 3, 7

MAGNETIC TYPE PRESSURE OPERATED SNAP SWITCH Filed Jan. 13, 1964 2 Sheets-Sheet 2 United States Patent 3,141,077 MAGNETIC TYPE PRESSURE OPERATED SNAP SWITCH Lyle Beernan, 758 Barrington, Grosse Pointe Park, Mich. Filed Jan. 13, 1964, Ser. No. 337,320 12 Claims. (Cl. 209-83) This invention relates to switches and particularly to switches which are responsive to fluid pressure to make and break electrical connections.

It is an object of this invention to provide a pressure switch of an improved construction which utilizes a minimum number of parts, is efficient, reliable and low in cost.

It is a further object of the invention to provide such a pressure switch which includes magnet assemblies and has a snap action.

It is a further object of the invention to provide such a pressure switch which has a novel mechanism for adjusting the pressure at which the switch contacts will close.

In the drawings:

FIGURE 1 is a vertical sectional view of a pressure switch embodying the invention taken along the line 1-1 in FIGURE 2.

FIGURE 2 is a sectional view taken along the line 22 in FIGURE 1.

FIGURE 3 is a sectional view taken along the line 33 in FIGURE 2.

FIGURE 4 is a sectional view taken along the line 4-4 in FIGURE 2.

FIGURE 5 is a sectional view taken along the line 5-5 in FIGURE 2.

FIGURE 6 is a fragmentary sectional view on an enlarged scale taken along the line 6-6 in FIGURE 2.

Referring to FIGURE 1, the pressure switch embodying the invention comprises a casing 10 having a base or bottom wall 11 and spaced side walls 12, 13 (FIG. 4). A U-shaped cover 14 is placed over the casing and includes peripheral flanges 15 which extend inwardly into contact with the outer surfaces of the walls 12, 13. Walls 12, 13 have conduit sections 16, 17 connected thereto through which electrical wires are threaded to the switch contacts.

As shown in FIGURE 6, bottom wall 11 is flat and has an enclosure 18 fastened thereon by screws 19 and defining a chamber 20 which communicates through a conduit 21 with a source of pressure. A diaphragm 22 of thin flexible material is interposed between the bottom wall 11 and the enclosure 18 and normally lies against and follows the contour of the inner surface of enclosure 18. A U-shaped pressure actuator 23 has a base 23a which rests on the diaphragm 22 and has legs 24 which extend upwardly through slots 25 in the bottom wall 11.

The movement of the diaphragm 22 due to pressure in the enclosure 18 is transmitted through the pressure actuator 23 to a spring support 25, the underside of which is engaged by the legs 24 of actuator 23. As shown in FIGURES l and 3, spring support 25 is generally flat and has hooks 26 bent upwardly from one end thereof which extend through slots 27 in a flange 23 which is bent upwardly from the bottom wall 11. The spring support includes upwardly bent side flanges 29 (FIGURE 6). A pin 30' extends upwardly from the bottom wall 11 through a coil spring 31. An adjustable nut 32 is threaded on the upper end of the pin 30 to vary the tension on the spring 31 which yieldingly urges the spring support 25 downwardly against the bottom wall 11. The magnitude of the force exerted by the spring 31 is varied by setting the nut 32 inwardly and outwardly on the pin 3t).

As shown in FIGURE 4, means are provided for varying the pressure at which the switch will close and comprises a leaf spring 33 which has one end thereof 34 en gaging the underside of spring support 25 and the other end thereof 35 engaged by a lighter weight helical spring 36 on a post 37, the tension of which is adjusted by a nut threaded on the post 37. The central portion of the spring 33 engages the top surface of wall 11 of the easing. The other end 35 of leaf spring 33 is bent down wardly and engages the bottom wall 11 of the casing as the spring support 25 moves upwardly to thereby limit the extent during which the spring pressure is applied on the spring support by the spring 36. Thereafter, the spring support 25 moves upwardly only in opposition to the action of spring 31.

Referring to FIGURES 3 and 5, a substantially flat armature 40 of magnetic material is formed at one end with upwardly turned flanges 41 which extend through slots 42 in a flange 43 bent upwardly from the other end of the bottom wall 11. The armature 40 is cut away, as at 44, so that it extends about but out of contact with the spring 31. Armature 40 is adapted to swing from a position in contact with a lower magnet assembly 45 to a position in contact with an upper magnet assembly 46.

As shown in FIGURE 3, the lower magnet assembly 45 comprises a magnet 47, preferably of ceramic type, and pole pieces formed by bending a tab 48 upwardly from the bottom wall 11 and by the flange 28. The upper magnet assembly 46 comprises a sheet metal bracket 49 that has tabs 50 bent therefrom to form pole pieces and a ceramic magnet 51 positioned between the pole pieces as by cementing. As shown in FIGURE 1, the ends 52 of the bracket 49 extend downwardly into contact with the walls 12, 13 and are held in position by screws 53. As shown in FIGURES 2 and 3, spring support 25 is cut away in the area of the lower magnet assembly 45.

In assembly of the switch, the screws 53 are loosened and the armature 48 is actuated from its lower position in engagement with the magnet assembly 45 to its upper position. Since the bracket 49 is pivotally mounted so that it can move with respect to the casing when the screws 53 are loosened, the magnet assembly 46 will swing to provide proper alignment of the magnet assembly 46 relative to the armature 40. The screws 53 can then be tightened and the magnet assembly 46 will thereafter be stationary and in proper position for successive engagement by the armature 40.

Referring to FIGURES 3 and 5, in order to provide a snap action, a post 55 is provided in fixed position on the support 25 and extends upwardly through an opening 56 in the armature 40. A nut 57 is threaded on the upper end of the post. A leaf spring 58 is interposed between the underside of the armature 40 and a nut 25a on the upper side of the support 25. Similarly, a leaf spring 59 is interposed between the nut 57 and the armature 40.

When the armature 40 is in its upper position with the free end thereof in engagement with the magnet assembly 46, the armature 40 also engages a switch actuator 60 of insulating material. Actuator 60 is mounted for movement in a contact block 64 and is yieldingly urged downwardly by a spring 61. When actuator 6t) is moved upwardly, lateral arms 62 thereon engage switch arms 63 on an insulator block 64 and thereby move contacts 65 out of engagement with contacts 66 on switch arms 67 (FIGURES 1 and 3).

In operation, when the fluid pressure is below the predetermined amount, as set by controlling the tension on the spring 31, switch contacts 65, 66 are closed, the spring support 25 is held in a downward position by the spring 31 and armature 40 is in magnetic contact engagement with the lower magnet assembly 45. When the fluid pressure reaches a predetermined amount, diaphragm 22 is flexed upwardly, causing the spring support 25 to swing upwardly. This action compresses the leaf spring 58 interposed between the spring support 25 and armature 4d. Continued movement of the spring support 25 fully compresses the leaf spring 58, the armature 40 remaining in magnetic contact with the lower spring assembly 45. When the spring 58 is fully compressed, spring support 25 upon further movement bodily moves the armature it) through direct engagement through the spring away from the magnet assembly 45. Immediately thereafter, the force of the compressed spring 58 causes the armature 40 to move upwardly in a snap action out of magnetic contact with lower magnet assembly 45 into magnetic contact with the upper magnet assembly .6. This moves the actuator 60 and breaks the electrical engagement between the contacts 65, 66.

As the pressure in the fluid line 21 decreases, the diaphragm 22 will move downwardly, permitting the support 25 to move downwardly under the action of the spring 31. This movement will initially be independent of the position of the spring 33 until the spring support 25 contacts the end 34 of the spring 33. When the spring support contacts the free end 34 of the spring 33, the spring 31 acting through the spring support 25 must overcome the action of the spring 33 before the spring support can move downwardly sufliciently to permit the armature to move. Because of this, the pressure at which the switch contact will close depends upon the force exerted by the spring 33. This could be adjusted by turning the nut 38. On the upstroke, the effectiveness of the spring 33 is limited by the stop 35 on the other end of the spring.

As the diaphragm moves downwardly and the spring support 25 moves downwardly, the leaf spring 59 is compressed between the nut 57 and the armature 40, the armature 4t remaining in magnetic contact with the magnet assembly 46. Continued movement of the spring support 25 fully compresses the leaf spring 59, and thereafter, the spring support 25 bodily swings the armature 40 through the direct engagement therewith through the spring 59 to swing the armature 45 away out of magnetic contact with the upper magnet assembly 46. Immediately after the magnetic contact of the armature it with the magnet assembly 46 is broken, leaf spring 59 having been compressed operates to move the armature quickly by a snap action into magnetic contact with the lower magnet assembly 45.

I have found that by spreading the nut 57 inwardly and outwardly on the post 55, the pressure at which the switch will close can be varied by varying the tension on the leaf spring 59. In such an arrangement, the leaf spring 33 (FIGURE 4) and the associated spring 36 and post 37 can be eliminated.

It can thus be seen that there has been provided a pressure switch which utilizes a minimum number of parts, which is reliable, efiicient, low in cost, and provides a snap action utilizing magnets.

What I claim is:

1. In a pressure switch, the combination comprising a casing,

a rigid spring support,

means for movably mounting said support to said casing,

spring means mounted on said casing and yieldingly urging said spring support in one direction,

an armature,

means for movably mounting said armature in said casing for engagement by said spring support,

said armature having a free end,

switch means mounted on said casing and operable by said armature,

pressure responsive means on said casing and operable on said spring support to move said support against the action of said spring means,

a pair of magnet assemblies mounted on said casing on opposite sides of the free end of said armature, said armature being movable from a position in magnetic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means.

2. In a pressure switch, the combination comprising a casing,

a rigid spring support pivoted to said casing,

spring means mounted on said casing and yieldingly urging said spring support in one direction,

an armature pivoted to said casing for engagement by said spring support,

said armature having a free end,

switch means mounted on said casing and operable by said armature,

pressure responsive means on said casing operable on said spring support to pivot said support against the action of said spring means,

a pair of magnet assemblies mounted on said casing on opposite sides of the free end of said armature, said armature being movable from a position in mag netic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means.

3. The combination set forth in claim 2 wherein one of said magnet assemblies is pivotally mounted on said casing.

4. In a pressure switch, the combination comprising a casing,

a rigid support pivoted to said casing,

a spring mounted on said casing and yieldingly urging said spring support in one direction,

an armature pivoted to said casing,

said armature having a free end,

pressure responsive means on said casing operable on said spring support to pivot said support in a direc tion against the action of said spring,

a pair of magnet assemblies mounted on said casing on opposite sides of the free end of said armature, switch means mounted on said casing, said armature being movable from a position in magnetic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means,

means for forming a lost motion connection between said armature and said support,

and yieldable means operable between said armature and said support to yieldingly resist the movement of said armature as the support is swung back and forth under the action of said pressure responsive means thereby producing a snap action.

5. In a pressure switch, the combination comprising a casing,

a rigid spring support pivoted to said casing,

a booster spring mounted on said casing and yieldingly urging said spring support in one direction,

an armature pivoted to said casing,

said armature having a free end,

pressure responsive means on said casing operable on said spring support to pivot said support in a direction against the action of said booster spring means,

a pair of magnet assemblies mounted on said casing on opposite sides of the free end of said armature, switch means mounted on said casing, said armature being movable from a position in magnetic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means,

a pin member on one of said armature and said support,

first spring means between said pin means and the other of said armature and said support,

and second spring means extending between said armature and said support, whereby when the pressure responsive means operates due to increased pressure to swing said spring sup port in a direction against the action of said booster spring means, one of said first and second spring means opposes momentarily the movement of the armature away from one magnet assembly and thereafter said one spring means swings the armature into engagement with the other magnet assembly in a snap action, and when said pressure responsive means operates due to reduced pressure to permit said booster spring to swing said spring support in an opposite direction, the other said first and second spring means momentarily opposes the movement of the armature away from said other magnet assembly and thereafter said one spring means swings the armature into engagement with the one magnet assembly in a snap action.

6. The combination set forth in claim 5 including means for adjusting the compression of said other spring means whereby the force opposing the movement of said armature away from said other magnet assembly may be adjusted.

7. The combination set forth in claim 6 including means for adjusting the compression of said first spring means whereby the force opposing the movement of said armature away from said other magnet assembly may be adjusted.

8. In a pressure switch, the combination comprising a casing,

a rigid spring support pivoted to said casing,

a booster spring mounted on said casing and yieldingly urging said spring support in one direction,

an armature pivoted to said casing,

said armature having a free end,

pressure responsive means on said casing operable on said spring support to pivot said support against the action of said booster spring means,

a pair of magnet assemblies mounted on opposite sides of the free end of said armature, switch means mounted on said casing, said armature being movable from a position in magnetic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means,

a pin member on said support and extending through said armature,

first spring means between said pin means and said armature,

and second spring means extending between said armature and said support,

whereby when pressure responsive means operates due to increased pressure to move said spring support in a direction against the action of said booster spring means, said first spring means temporarily opposes the movement of the armature away from one magnet assembly until sufficient force is applied and thereafter said first spring means swings the armature into engagement with the other magnet assembly in a snap action, and when the pressure responsive means operates due to decreased pressure to permit said booster spring to swing said spring support in an opposite direction, said second spring means momentarily opposes the movement of said armature away from the other magnet assembly and thereafter said second spring means swings the armature into engagement with the other magnet assembly in a snap action.

9. In a pressure switch, the combination comprising a casing,

a rigid spring support pivoted to one side of said casing,

a booster spring mounted on said casing and yieldingly urging said spring support in one direction,

an armature pivoted to an opposite side of said casing,

said armature having a free end,

pressure responsive means on said casing operable on said spring support to pivot said support in a direction against the action of said booster spring means,

a pair of magnet assemblies mounted on opposite sides of the free end of said armature,

switch means mounted on said casing,

said armature being movable from a position in mag netic contact with one magnet assembly to a position in magnetic contact with the other magnet assembly,

said armature in one of said positions actuating said switch means,

a pin member on one of said supports extending through said armature, t

first spring means between said pin means and said armature,

and second spring means extending between said armature and said support,

whereby when pressure responsive means operates due to increased pressure to move said spring support in a direction against the action of said booster spring means, said first spring means temporarily opposes the movement of the armature away from one magnet assembly until sufiicient force is applied and thereafter said first spring means swings the armature into engagement with the other magnet assembly in a snap action, and when the pressure responsive means operates due to decreased pressure to permit said booster spring to swing said spring support in an opposite direction, said second spring means momentarily opposes the movement of said armature away from the other magnet assembly and thereafter said second spring means swings the armature into engagement with the other magnet assembly in a snap action.

10. In a pressure switch, the combination comprising a sheet metal casing having a base,

a first flange bent upwardly from said base,

a rigid spring support pivoted to said first flange,

a booster spring mounted on said casing and yieldingly urging said spring support in one direction,

said base having a second flange bent upwardly from the other end of said base,

an armature pivoted to said second flange,

said armature having a free end,

a pressure responsive diaphragm means mounted on said base,

an actuator interposed between said diaphragm and said base and operable on said spring support to pivot said support in a direction against the action of said booster spring,

a pair of magnet assemblies mounted on said casing on each side of the free end of said armature,

said armature being movable from a position adjacent one magnet assembly to a position adjacent the other magnet assembly,

switch means mounted on said casing,

said armature in one of said positions actuating said switch means,

a pin member on said support and extending through said armature,

first spring means between said pin means and said armature,

and second spring means extending between said armature and said support,

whereby when pressure responsive means operates due to increased pressure to move said spring support in a direction against the action of said booster spring, said first spring means temporarily opposes the movement of the armature away from one magnet assembly until sufiicient force is applied and thereafter said first spring means swings the armature into engagement with the other magnet assembly in a snap action, and when the pressure responsive means operates due to decreased pressure to permit said booster spring to swing said spring support in an opposite direction, said second spring means momentarily opposes the movement of said armature away from the other magnet assembly and thereafter said second spring means swings the armature into engagement with the other magnet assembly in a snap action.

11. The combination set forth in claim 10 wherein one said magnet assembly comprises a ceramic magnet, a tab bent upwardly from said base forming one pole piece and said second flange of said base forming another pole piece.

12. The combination set forth in claim 10 wherein said other magnet assembly comprises a bracket, means 10 for adjustably mounting said bracket on said casing, said bracket having a base and flanges bent from said base to form pole pieces, and a ceramic magnet mounted on said base between said pole pieces.

References Cited in the file of this patent UNITED STATES PATENTS 2,232,243 Judson Feb. 18, 1941 I 2,452,425 Berkholdcr Oct. 26, 1948 2,635,157 Flight et a1 Apr. 14, 1953 

1. IN A PRESSURE SWITCH, THE COMBINATION COMPRISING A CASING, A RIGID SPRING SUPPORT, MEANS FOR MOVABLY MOUNTING SAID SUPPORT TO SAID CASING, SPRING MEANS MOUNTED ON SAID CASING AND YIELDINGLY URGING SAID SPRING SUPPORT IN ONE DIRECTION, AN ARMATURE, MEANS FOR MOVABLY MOUNTING SAID ARMATURE IN SAID CASING FOR ENGAGEMENT BY SAID SPRING SUPPORT, SAID ARMATURE HAVING A FREE END, SWITCH MEANS MOUNTED ON SAID CASING AND OPERABLE BY SAID ARMATURE, PRESSURE RESPONSIVE MEANS ON SAID CASING AND OPERABLE ON SAID SPRING SUPPORT TO MOVE SAID SUPPORT AGAINST THE ACTION OF SAID SPRING MEANS, A PAIR OF MAGNET ASSEMBLIES MOUNTED ON SAID CASING ON OPPOSITE SIDES OF THE FREE END OF SAID ARMATURE, SAID ARMATURE BEING MOVABLE FROM A POSITION IN MAGNETIC CONTACT WITH ONE MAGNET ASSEMBLY TO A POSITION IN MAGNETIC CONTACT WITH THE OTHER MAGNET ASSEMBLY, SAID ARMATURE IN ONE OF SAID POSITIONS ACTUATING SAID SWITCH MEANS. 